Large red Felguard, attacks for both physical and shadow damage. Disarming is a good idea but he parries a lot.

Heroic

He hits the tank for between 3-4k damage and his Deafening Roar silences as well as causing approximately 2-2.5k damage. Have the tank position themself against a wall in an archway with the Unbound Devastator opposite them. You can position healers such that they're diagonally from the tank and in range of heals but also out of LOS of the mob. This prevents the silence from taking place on the healers which can easily wipe a group.

For DPS classes, stay out of LOS until the tank gets the Shout debuff then proceed in to DPS for about 10seconds. Run out of LOS, wait for the debuff on the tank and run back in. Rinse and repeat.